MOSS SP2 with K2 black pearl

take a look at this: http://srikantha.wordpress.com/2009/05/03/sharepoint-sp2-and-k2/

Offical word is that it has not been fully tested with 0807 so it is not officially supported yet.

The official support is planned for the next blackpearl update 090x.

However, if you have already installed MOSS SP2 and it works fine for you, then that's great.  However, if you hit issues after your installation, take note that it will not be supported.